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'Formylation' in keywords Facet   Publication Year 2001  [X]
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2001[X]
1Author    Georg Ziegler3, Erwin Haug3, Wolfgang Freyb, Willi Kantlehner3Requires cookie*
 Title    Orthoamide, LVII [1]. Lassen sich aromatische Aldehyde nach Fries aus Arylformiaten hersteilen? Orthoamides, LVII [1]. Can Aromatic Aldehydes be Prepared from Aryl Formates via the Fries Rearrangement?  
 Abstract    The aromatic hydroxyaldehydes 3a-3g, 5a-5f, 8 , 10 can be prepared by the action of BC13, BBr3 or trifluoromethanesulfonic acid, on the aryl formates la-lf, 4a-e, 7, 9 via Fries rear­ rangement. BBr3 is more effective than BC13. The activating ability of BBr3 can be improved by addition of FeCl3. Rearrangements which are induced by trifluoromethanesulfonic acid can give rise to the formations of regioisomers, which might be different from the products formed when the reaction is performed with Lewis acids. The yields of the aldehydes are lowered by subsequent condensation reactions. This view was confirmed by the isolation of a con­ densation product, which was characterized as a dibenzo[a,y']xanthene derivative 6 by crystal structure analysis. For the Fries rearrangement of formyl groups a new mechanism is proposed. 2-Hydroxy-1-naphthaldehyde 5c can be obtained in good yield from formic acid, BBr3, and 2 -naphthol. 
  Reference    Z. Naturforsch. 56b, 1178—1187 (2001); eingegangen am 13. Juli 2001 
  Published    2001 
  Keywords    Aromatic Hydroxyaldehydes, Fries Rearrangement, Formylation 
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 TEI-XML for    default:Reihe_B/56/ZNB-2001-56b-1178.pdf 
 Identifier    ZNB-2001-56b-1178 
 Volume    56 
2Author    Georg Ziegler, Willi KantlehnerRequires cookie*
 Title    Orthoamides, LVI [1]. A New Method of Wide Scope for the Preparation of Aryl Formates  
 Abstract    26 are prepared by formylation of hydroxyarenes 3a-u, 25 with /V,Af-diformylacetamide (1) or triformamide (2), respectively, in fairly good yields. The reactions can be catalyzed by sodium diformamide or praseodymium(III) triflate. The thiolformate 28 was obtained analogously from 1-thionaphthol (27). 
  Reference    Z. Naturforsch. 56b, 1172—1177 (2001); received July 13 2001 
  Published    2001 
  Keywords    Aryl Formates, Formylation, Hydroxyarenes Aryl formates 4a-u, 6 
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 TEI-XML for    default:Reihe_B/56/ZNB-2001-56b-1172.pdf 
 Identifier    ZNB-2001-56b-1172 
 Volume    56